The proposed coordinating center will have primary responsibility for the collection, storage, and analysis of all data and will insure, in part, that each participating clinic abides by the provisions of the protocol. The goals of this study are to determine if the argon laser is useful in the management of branch vein occlusion and its complications as follows: A) Major branch vein occlusion wthout neovascularization: 1) Improve or maintain visual acuity; 2) Improve or prevent macular edema; 3) Prevent the development of neovascularzation. B) Major branch vein occlusion with neovascularization: 1) Improve or maintain visual acuity; 2) Control or destroy neovascularization; 3) Prevent vitreous hemorrhage and/or retinal detachment; 4) Improve or prevent macular edema. C) Macular branch vein occlusion with macular edema and decreased vision: 1) Improve or maintain visual acuity; 2) Improve macular edema.